Generally, cyclopropene derivatives can be prepared by reacting allyl halides with strong bases [J. Org. Chem. 30 (1965) 2089-2090; and J. Org. Chem. 36 (1971) 1320-1321]. In addition, with reference to some recent publications including U.S. Pat. No. 5,518,988, it can be seen that cyclopropene compounds having a relatively simple structure, such as cyclopropene, 1-methylcyclopropene and the like, exhibit excellent inhibitory effects on the ripening process of plants [J. Agric. Food Chem. 53 (2005), 7565-7570; J. Agric. Food Chem. 51 (2003), 4680-4686; J. Agric. Food Chem. 51 (2003), 3858-3864; J. Agric. Food Chem. 51 (2003), 1189-1200; and J. Agric. Food Chem. 47 (1999), 2847-2853].
In particular, among these cyclopropene compounds, cyclopropene (boiling point of −36 to −35° C./744 mmHg) and 1-methylcyclopropene (boiling point of 12° C./760 mmHg) is present in a gaseous phase at room temperature and therefore can be easily treated throughout a storage space of agricultural products, even without an additional spray device.
However, the cyclopropene compounds including cyclopropene and 1-methylcyclopropene are chemically unstable. Therefore, if such cyclopropene compounds are not stored at a low temperature (below −100° C.), they may easily undergo loss of their chemical properties through dimerization etc. In order to solve the problems associated with the storage of these compounds, a variety of research has been actively undertaken to find a method for safe storage of the cyclopropene compounds.
For example, U.S. Pat. Nos. 6,017,849, 6,426,319, 6,444,619, 6,548,448, 6,762,153 and 6,953,540 disclose safe storage methods of cyclopropene derivatives, particularly 1-methylcyclopropene and application thereof to target sites. That is, these patents disclose the encapsulation of small molecules such as 1-methylcyclopropene into macromolecules such as α-cyclodextrin. More specifically, 1-methylcyclopropene is safely stored using α-cyclodextrin, and α-cyclodextrin complex containing 1-methylcyclopropene is treated with water, upon using thereof for desired applications. The added water molecules gradually infiltrate into α-cyclodextrin, thus leading to the release of 1-methylcyclopropene to the outside, and therefore the released 1-methylcyclopropene acts on plants to thereby inhibit the action of ethylene.
However, the above-mentioned techniques suffer from various disadvantages such as a difficulty to prepare 1-methylcyclopropene, a separate process of adsorbing 1-methylcyclopropene to α-cyclodextrin after preparation of 1-methylcyclopropene, a treatment of the 1-methylcyclopropene-containing α-cyclodextrin complex with water to release 1-methylcyclopropene from the complex for treatment of 1-methylcyclopropene on the plants, thus resulting in a long processing time and know-how for such treatment, consequently high processing costs.
To this end, as discussed hereinbefore, there is a strong need for the development of a technique which is capable of achieving convenient in situ preparation of cyclopropene derivatives in a simplified manner, followed by direct treatment thereof to the plants.